Abstract: To ensure the stability of old landslides after the activation, it is important to study the landslide triggering prevention and control measures for the regional geological hazard prevention and safety control. This paper presents a case history of the evaluation of an existing old landslide in Shenzhen. Different evaluation methods, such as, topographic survey, geotechnical test boring, engineering geological mapping and investigation, drilling, and other in-situ testing, were performed to comprehensively analyze the natural geographic and geological environmental conditions and landslide characteristics. The landslide stability was analyzed using the unbalanced thrust transfer coefficient method from the landslide prevention and control plan point of view. The results show that the landslide was triggered by the activation of an old landslide. Two sections of the landslide, the western section of the landslide was in the shape of a skip on the plane, and the eastern section of the landslide was in the shape of a round chair on the plane view. The heavy rainfall duration of six consecutive days at the end of the August was the direct factor that leading to the activation of the landslide. It is proposed that the anti-slip piles can be used in the anti-slip section of the front edge of the landslide for mitigation, and the upper part of the landslide body in some sections of the slope was set with anchor lattice beam reinforcement and other reinforcement measures, which provide reference for the investigation.

Key words: Old Landslide, Formation Mechanism, Stability Analysis, Prevention Measures